The zebrafish Danio rerio has emerged as a premier model organism for biomedical research in a variety of disciplines. Despite this prominence, the community of researchers using zebrafish still lacks a normal table of post-embryonic zebrafish development that would allow the accurate and repeatable staging of fish throughout the life cycle. These later stages of zebrafish development are an important model for human health and disease, and there is increasing interest in elucidating the developmental, genetic, and physiological bases for this transition from embryo to adult. Such efforts would be greatly facilitated by a standardized set of staging criteria that can be rapidly and precisely applied to living fish. To these ends, the investigator will compile a normal table of post-embryonic zebrafish development. He will identify stages based on the states of externally visible traits that can be seen in living fish by standard light microscopy (e.g., swim bladder, gut, scales, fins, pigment pattern, size, and shape), as well as traits that are visible by fluorescence microscopy after staining fish with vital fluorescent dyes (calcein for bone, DASPEI for the lateral line sensory system). As zebrafish development is extremely plastic, the investigator will further validate these staging criteria at different growth rates and temperatures. Finally, he will make this normal table of development available both in print and by the World Wide Web via the Zebrafish Information Network. This resource will greatly enable studies of post-embryonic zebrafish development and will facilitate the generation of new models for normal human development and disease states. [unreadable] [unreadable]